1. Department of Anesthesiology and Pain Medicine, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea
2. Department of Policy Research Affairs, National Health Insurance Service Ilsan Hospital, Goyang, Korea
3. Department of Anesthesiology and Pain Medicine and Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea
4. Department of Anesthesia and Pain Medicine, Pusan National University School of Medicine, Yangsan, Korea